Cassel helped the Vikings get their first victory of the season with a solid performance in London against Pittsburgh Sept. 29, a game Christian Ponder sat out of because of a broken rib. Ponder was cleared to play this week, though. Despite Frazier's earlier statement that Ponder was still the starter when healthy, the Vikings decided to make the former first-round draft pick their backup.

Frazier said his mind was made up a couple of days ago.

"I think it's always tough when you make a change at quarterback," he said. "You have to take a lot of factors into it when you're doing that. You don't make those decisions lightly, and we didn't. We'll see how it plays out."

The Vikings signed ex-Tampa Bay quarterback Josh Freeman this week, further muddling the position. Frazier wasn't ready to declare Freeman an option for the next game, Oct. 21 on the road against the New York Giants, but he said he'd re-evaluate the situation Monday.

Cassel is 30-33 in 63 career starts, most of them with Kansas City. He said he didn't find out until Friday.

"I've been focusing on it without really knowing but at the same time anticipating maybe this would happen," Cassel said. "You know what? You never know in this league. I wouldn't have guessed on Monday we'd have another quarterback in the room as well."

After practice Thursday, Ponder acknowledged the mental challenge of the last few weeks.

"I would be lying if I didn't say it's a little disappointing and frustrating," he said. "But I'm not going to get too discouraged about it. I'm a man of faith and I know God is in control."

Ponder said a trade "would be difficult to deal with" but that he was trying not to worry about the future of his career. Picked 12th overall in the 2011 draft, Ponder is 12-17 as a starter with 39 turnovers.

"It's a waste of energy and thought to think about what could happen and what might not happen," he said. "I'm just trying to enjoy these moments because life in the NFL doesn't last long."

The Vikings also listed kicker Blair Walsh as questionable for Sunday due to tightness in his hamstring that kept him out of practice the last two days. Punter Jeff Locke would be the emergency replacement, but Frazier said he's anticipating Walsh will play against the Panthers.

Cornerback Chris Cook (groin) and safety Jamarca Sanford (hamstring) are expected back in the starting lineup after missing the Steelers game with injuries.